1. Field of the Invention
The invention relates generally to the field of magnetic recording, and more particularly, to a compliant guide assembly for providing a biasing force to an edge of a tape to precisely position the tape as it passes a read/write head.
2. Related Art
Magnetic tape is used extensively in the computer and data processing industries for storing large quantities of data. Data is read from and written to a tape using a tape transport. The data is generally written to the tape in a longitudinal, multi-track format.
In order for a magnetic tape head to read data from and write data to a tape, it is important that the tape be precisely aligned with the head. This alignment assures that each track on the tape aligns with corresponding read and write gaps in the tape head.
Lateral alignment of the tape to the head has been conventionally performed by positioning a tape guide adjacent the head. The tape guide defines a reference surface perpendicular to the plane of the tape. By bringing an edge of the tape into precise contact with the tape guide, the position of the tape with respect to the head is assured. A compliant guide assembly is used to bias the opposite edge of the tape against the tape guide.
The conventional compliant guide assembly includes a spring assembly having a body with a plurality of cantilever spring elements extending outward therefrom. Each spring element has a ceramic guide button attached to its distal end. The spring assembly is photo etched from a sheet of stainless steel. The ceramic guide buttons are then bonded to each of the cantilever spring elements. The guide buttons contact the edge of the tape to urge the opposite edge of the tape against the tape guide.
Conventional compliant guide assemblies tend to provide varying and unpredictable biasing forces on the tape. If the applied biasing force is too great, it can cause the tape to buckle near the read/write head. This can cause data read errors. If the biasing force is too small, then the tape may lift from the tape guide, resulting in a loss of alignment between the read/write gaps and the data tracks on the tape.
A number of variables contribute to the unpredictability of the biasing force exerted by each cantilever spring element of the compliant guide assembly. These include variations in the thickness of the spring material, an initial offset of a spring element from a nominal position due to curvatures in the spring material, variations in the width of each cantilever spring element, variations in the length of each cantilever spring element, variations in the modulus of elasticity of the spring material, variations in the width of the tape, variations in the thickness of the guide button, and variations in the thickness of the adhesive commonly used to bond the guide button to the cantilever spring element.
The conventional compliant guide assembly is inexpensive to manufacture. However, the variance and unpredictability of the forces exerted by each cantilever spring element may be unacceptable for certain tape transport applications. For example, as track widths and track pitches become smaller in an attempt to increase areal densities (i.e., data per unit area), the need for precise tape/head positioning becomes increasingly important.
What is needed is a compliant guide assembly that exerts a more uniform biasing force to the edge of a tape.